Diffusion-weighted magnetic resonance imaging (MRI) techniques are known in the field of medical diagnosis and medical diagnostic imaging. In diffusion-weighted MRI, the degree of anisotropic diffusion can be indicative of pathology or disease. Thus, an accurate metric for diffusional anisotropy can be an important biomarker for diseases such as multiple sclerosis and traumatic brain injury. However, in the brain, neuronal fibers of multiple directionalities may be present within any given voxel, complicating the measurement of anisotropic diffusion.